/**
 * Copyright (C) 2002-2015   The FreeCol Team
 * <p>
 * This file is part of FreeCol.
 * <p>
 * FreeCol is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 * <p>
 * FreeCol is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * <p>
 * You should have received a copy of the GNU General Public License
 * along with FreeCol.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.sf.freecol.common.networking;

import net.sf.freecol.common.model.Game;
import net.sf.freecol.common.model.TradeRoute;
import net.sf.freecol.server.FreeColServer;
import net.sf.freecol.server.model.ServerPlayer;

import org.w3c.dom.Element;


/**
 * The message sent when updating a trade route.
 */
public class UpdateTradeRouteMessage extends DOMMessage
{

    /** The trade route to update. */
    private final TradeRoute tradeRoute;


    /**
     * Create a new <code>UpdateTradeRouteMessage</code> with the
     * supplied trade route.
     *
     * @param tradeRoute The <code>TradeRoute</code> to update.
     */
    public UpdateTradeRouteMessage( TradeRoute tradeRoute )
    {
        super( getXMLElementTagName( ) );

        this.tradeRoute = tradeRoute;
    }

    /**
     * Create a new <code>UpdateTradeRouteMessage</code> from a
     * supplied element.
     *
     * @param game The <code>Game</code> this message belongs to.
     * @param element The <code>Element</code> to use to create the message.
     */
    public UpdateTradeRouteMessage( Game game, Element element )
    {
        super( getXMLElementTagName( ) );

        tradeRoute = ( element.getChildNodes( ).getLength( ) != 1 ) ? null
                : SetTradeRoutesMessage.tradeRouteFromElement( game,
                                                               ( Element ) element.getChildNodes( ).item( 0 ) );
    }


    /**
     * Handle a "updateTradeRoute"-message.
     *
     * @param server The <code>FreeColServer</code> handling the message.
     * @param connection The <code>Connection</code> message was received on.
     *
     * @return An update containing the updateTradeRouted unit,
     *         or an error <code>Element</code> on failure.
     */
    public Element handle( FreeColServer server, Connection connection )
    {
        final ServerPlayer serverPlayer = server.getPlayer( connection );

        if ( tradeRoute == null || tradeRoute.getId( ) == null
                || ! SetTradeRoutesMessage.hasPrefix( tradeRoute ) )
        {
            return DOMMessage.clientError( "Bogus route" );
        }

        String id = SetTradeRoutesMessage.removePrefix( tradeRoute );
        TradeRoute realRoute;
        try
        {
            realRoute = serverPlayer.getOurFreeColGameObject( id,
                                                              TradeRoute.class );
        }
        catch ( Exception e )
        {
            return DOMMessage.clientError( e.getMessage( ) );
        }

        realRoute.updateFrom( tradeRoute );
        tradeRoute.dispose( );
        return null;
    }

    /**
     * Convert this UpdateTradeRouteMessage to XML.
     *
     * @return The XML representation of this message.
     */
    @Override
    public Element toXMLElement( )
    {
        Element result = createMessage( getXMLElementTagName( ) );
        result.appendChild( tradeRoute.toXMLElement( result.getOwnerDocument( ) ) );
        return result;
    }

    /**
     * The tag name of the root element representing this object.
     *
     * @return "updateTradeRoute".
     */
    public static String getXMLElementTagName( )
    {
        return "updateTradeRoute";
    }
}
